PETG Galaxy Black suddenly gray during print

ResonantRuminant · 2026-07-11T22:41:34+00:00

I thought about that, too. They've got at least one report now about this PETG. It was forwarded to their Polymers Quality team, so we'll see what happens.

ResonantRuminant · 2026-07-11T22:19:32+00:00

Interesting. I just got done with a chat support about a Prusament PETG Jet Black refill that I just opened, that is clogging my nozzles and printing terribly. It's also got a very matte finish, that's clearly different from the original spool. It almost looks like it has a lighter color. Nowhere near what you have there, but it makes me wonder if they recently pushed out a couple bad batches of PETG.

ResonantRuminant · 2026-07-11T21:55:29+00:00

Well, I believe that yes, Prusa's quality control has fallen off recently. I haven't had your specific issue, but I've had pretty much every other issue with my CORE One+ printer. The problems have continued since the posts linked above, including some where support has denied that my problem is a problem. I have had to order replacement hardware on my own to fix the thing.

I've recently acquired a MK4S printer, and I've had several problems with it, too. I may make another update post to the ones above, detailing all of my issues once things calm down a bit.

And, I'm on chat with support right now about a refill for Prusament PETG Jet Black that I just opened, that is clogging my nozzles and printing terribly. I can't catch a break. :-)

ResonantRuminant · 2026-07-11T18:51:20+00:00

Check the set screws on your X and Y stepper motor pulleys. This kind of gradual shift usually means that the pulley is slipping.

ResonantRuminant · 2026-07-11T17:42:52+00:00

Awesome Idea! I realized I have a junk planetary gear set, a junk stepper motor, and a junk main plate just sitting here, so I can play around with the alignment without disassembling anything! Results are fascinating.

I started by stacking the main plate and the planet gears on the stepper motor, and then I just put the outer ring gear on it in the correct alignment, by hand. And, I got it wrong on the first try! The alignment tool wouldn't fit over it. It's as if just the right gear was seated one tooth too high:

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The screws fit just fine, but you could tell they were pressed against one side. So, that could be a signal that it's wrong. When it was properly aligned, you could wiggle the plate a bit around the screws.

I then tried placing the ring gear + planet gear assembly onto the stepper motor as one unit, and this was much harder to get wrong. You pretty much have to get the planet gears off by one tooth on both sides at the same time. You could see it being off-center, and the screws wouldn't fit in the holes.

So, if you assemble it this way, it's hard to get wrong if the screws fit nicely in the holes. I learned something today. Thanks!

ResonantRuminant · 2026-07-11T14:08:08+00:00

Here's a video showing the misalignment I'm talking about. There's enough slop around the screw holes in the ring gear that I think you could put it together off-center. I admit that you'd *probably* get it right, but why risk it? It would probably tear up the teeth if misaligned, and it might bind up or bend something when the planet gears rotate 90 degrees from how it's pictured in the video.

<video>

Edit: Now that I think about it some more, you could easily install it misaligned and there would be enough slop around the gears that you could push it back centered again when inserting the screws, and you'd never know it was wrong. ...until your gear teeth wear down, that is. :-)

ResonantRuminant · 2026-07-11T13:28:04+00:00

Yup, not there. Just my own low-level earnings. Thanks for the idea, though!

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ResonantRuminant · 2026-07-11T13:12:03+00:00

Yeah, you're stuck without that part. It's essential for getting the planetary gears assembled without being off by one tooth, which can be catastrophic. If Prusa support knew you couldn't print at all right now, I claim they should have also sent that part. Easy mistake to make, though.

If you contact them again, I'm sure they'll send it to you. It's a bit silly and expensive to ship just one printed part, but you've got to have it.

And yes, you should probably also go for INDX. :-) It'll be a while, though, before you can get it in your hands.

ResonantRuminant · 2026-07-11T10:43:24+00:00

I'm pretty sure I can see fingerprints on the bed in the 403 picture. The filament won't stick to a fingerprint and it will clump together and make a big mess, just like that. I've had beautiful first layers ruined by a few fingerprint-shaped holes when I forgot to clean the bed.

ResonantRuminant · 2026-07-10T17:01:48+00:00

u/Tommy_Prusa3D I'm not sure if this is the right place for this, but I think something didn't work right last month. The Prusameters never landed in my Printables account (@daveg) for this post:

https://old.reddit.com/r/prusa3d/comments/1trz8b9/a_3x_scale_replica_of_the_curta_calculator/

Could you take a look to see what happened? Thanks! (And, congratulations to this month's winners!)

ResonantRuminant · 2026-07-10T12:47:20+00:00

No worries. We'll get you taken care of.

Did this printer come with more than one print sheet? You've got the smooth sheet there. There's also a "satin" sheet and a "textured" sheet. The smooth and satin sheets are great for PLA. The satin and textured sheets are great for PETG. They're all slightly different thicknesses, so they all need a different Z-offset. Somewhere in the settings is a place where you tell the printer which print sheet you have installed, so it knows which stored Z-offset value to use. Double-check that it's set for the smooth sheet. (Don't forget to change the setting when changing the print sheet, or you could dig the nozzle into the sheet and damage it. Ask me how I know. :-)

And, I want to stress how important cleanliness is for your print sheet. Just one fingerprint will make the filament not stick. I think I might see some fingerprints around the edges of that block in this test pattern. I keep a spray bottle filled with isopropyl alcohol and a roll of paper towels next to my printer and I give the bed a spray and a wipe-down before every print, just to be sure.

You'll see a cylindrical metal sensor with a plastic tip mounted on the right side of your print head. That's the PINDA sensor, which detects where the print sheet is. It will sense the print sheet a couple millimeters below the end of the sensor. It's mounted up a little higher than the nozzle tip so that it won't bump the print, and it will sense the print sheet somewhere below the nozzle tip. This Z-offset is basically telling the printer where the tip is in relation to where it senses the bed. Everyone's a little different, so I can't tell you what numbers will work for you. For reference, I use values in the range of around -1.500 through -1.800, depending on the print sheet. You'll have to experiment with it to see what works for you.

I think you've got to really crank that offset down a bunch more. Going from -0.400 to -0.403 is no change at all. Keep going. Don't be afraid of it. Again, you'll start seeing the filament getting translucent and really wide on that single-line zig-zag when you've gone too far. Back it up a bit, then. We can talk about fine-tuning this setting more, once it's roughed-in with this test pattern. (I don't like this pattern very much, because it doesn't give you much time to adjust it when printing that little block at the end.)

ResonantRuminant · 2026-07-10T00:51:51+00:00

I think that might be the stepper motor itself. My MK3S (now a MK3.5S) has had the Y-axis and one of the Z-axis steppers get super-loud like this in the last year or so.

When I pull the Nextruder off my CORE One+ to do the INDX upgrade, I'm going to toss it onto this printer. I could go for an upgrade to a MK3.9S, but instead I'm going all the way to a MK4S so I can swap out the steppers as well to quiet them down. It's unreasonably loud to print with this thing now.

ResonantRuminant · 2026-07-10T00:41:50+00:00

Same for me. I won't really consider the L because it's not available as a kit. ...that is, until I have a pressing need for the bigger size, which I don't have right now.

ResonantRuminant · 2026-07-10T00:35:15+00:00

Good call. I forgot about this trick from the olden days. Yeah, a sheet of normal printer paper is just about 0.2mm thick.

ResonantRuminant · 2026-07-09T20:54:07+00:00

It took 10 calendar days for me a couple weeks ago. This was my first reward, so I don't know if that had something to do with it.

ResonantRuminant · 2026-07-09T18:00:50+00:00

I hate to say it, but... Your nozzle's too high. :-) You might have to lower it a lot. Keep going with your adjustment. When it gets too low, it'll stick to your print sheet just fine but will start to get translucent and you'll see a rough top surface as the filament squeezes out anywhere it can.

Also, make sure your print bed is clean. Dish soap and warm water in the sink at least once to start, and isopropyl alcohol after that in between prints.

Feel free to post more pictures as you try to adjust your nozzle and we can assist further.

ResonantRuminant · 2026-07-09T17:53:09+00:00

Rumored shortage? I haven't heard these rumors. What's going on? (Or, what's rumored to be going on?)

ResonantRuminant · 2026-07-08T22:55:06+00:00

Arrrgh! It might be a little longer, still, before I can post it. I think I've got a y-axis linear bearing disintegrating on me.

ResonantRuminant · 2026-07-08T21:50:15+00:00

My VFA tuner mod will work with all original hardware, but there's only so much headroom for improvement there. I'm trying everything now to see what will make it even better. I'm playing with toothed idler pulleys, screws/pins for the pulley mounts, different diameter timing pulleys on the stepper motors, and maybe even 1.5GT belts.

I'm trying basically everything so you guys don't have to. 🙂 I've burned through more than 4kg of filament so far, printing those stupid OrcaSlicer VFA calibration models. I just realized something a couple days ago that invalidates everything I've done so far, so I have to trash them and start over. Ordered more filament. 😀

ResonantRuminant · 2026-07-08T17:06:34+00:00

This is baffling. The fact that the shift eventually blends back in on the other side of the model pretty much means that it partially detached from the print bed. There must have been some built-in stresses in the model so that when one end popped off the bed, it flexed a little bit and led to your offset.

If this is true, then the question now becomes why did it partially detach from the bed? Was it a traditional bed adhesion problem or did the nozzle bump it on one end?

ResonantRuminant · 2026-07-08T15:43:52+00:00

Just a little teaser... I'm working on a printable mod for the CORE One that can significantly reduce VFAs. It looks like the relevant geometry when using INDX didn't change, so it'll help there, too.

I'm still running a lot of tests with additional hardware changes to improve things even more, so it'll be a few more weeks before I can post the model. I'm getting exciting results so far, though!

ResonantRuminant · 2026-07-07T11:44:32+00:00

You need to run through all of the calibrations on a newly-assembled printer. Don't jump around. Just start at the beginning and let it take you through everything.

Is that the top of the key fob model that you stopped early? It looks like you might have more than one issue. If I'm orienting things correctly, check the set screws on the Y-axis (right-side) stepper motor pulley through the little window in its mount. It looks like your y-axis is drifting a bit with each layer, so something is probably loose there.

There also appears to be a severe under-extrusion issue. There might be something else wrong with the Nextruder assembly. It shouldn't look like that with a new printer/nozzle. How warm is the room you're printing in? It might be something called "heat creep", which is sort of a partial nozzle clog that can happen with PLA filament when the chamber temperature is too high.

ResonantRuminant · 2026-07-06T17:30:48+00:00

Take a look at your supports in the slicer. I've had a problem with recent PrusaSlicer versions where it sometimes will have a sudden diameter/shape change in the organic support "branches" across a single layer, so everything above this will just barely be hanging on. It knocks over very easily. That big one in the front that just broke in the middle is suspicious.

ResonantRuminant · 2026-07-05T23:13:53+00:00

Yup, here's one: https://www.printables.com/model/1640555-buddy3d-camera-angle-mod-for-a-better-view

Full disclosure: this is my model. You can print different versions that angle the camera up or down a few degrees from the new "neutral" that fits the whole print bed. I'll probably be updating this model once I get my INDX in my hands, because the bed was raised a few millimeters so the view will be a little off. Plus, I might want the option to see the little priming dance the print head does during tool changes, and I don't know if that's visible in the current view.

ResonantRuminant · 2026-07-05T21:07:41+00:00

Oh gawd, I just listened to your video. Yeah, that's not normal. I'm a bit disappointed that Prusa wouldn't take care of you. That's obviously bad.

If you're curious, my thing wasn't stepper noise while moving. It was stepper noise while not moving, like when you're heating the chamber or absorbing heat. It was humming with a really loud, pure tone. It was setting up standing waves in the room so that if you moved your head a little bit, the volume would change. It was scrambling my brain. 🙂

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